[Glade-devel] Extending glade

[james daa com au (James Henstridge)]

Alberto Mardegan wrote:

> Hi all!
>  I'm quite new to Glade and Gtk+ in general, and I don't know much of
> how they work.
> I'd like to add some custom widgets (a date/time widget comes to mind)
> to glade (and therefore libglade, since I intend to keep the interface
> part on the XML file), but I don't know what's the best way to do it
> actually.
>
> Googling around, I've come to this page of the libglade manual,
> http://developer.gnome.org/doc/API/libglade/libglade-extending.html
> which states that, except using the custom widget class (which I won't
> do), the solution is modifying the libglade sources.
>
> I've looked at the source code of both glade and libglade, and it seems
> to me that modifying the sources to add my widgets will not be very
> difficult, since there is not too much work to be done.
>
> But is there a way to avoid modifying the sources?
> Isn't there a way in Gtk+ to create a widget from a class name, i.e.
> a function like
>
> GtkWidget *gtk_new(const gchar *classname)
>
> and then retrieve the modifiable properties of the newly created object,
> in order to let the user change them in glade?
>
> I found some old discussion about something like that, but they are old:
>
> http://rpmfind.net/tools/glade/messages/2431.html
> http://lists.ximian.com/archives/public/glade-users/2000-November/000233.html
>
> What is the actual status of these ideas?
>  
First off, I assume you are using GTK 2.x (as opposed to 1.2.x).  If you 
aren't, then switch now.

Libglade 2.0.x makes heavy use of the property system of GTK.  This 
means that if you expose all the functionality of your new widget as 
properties (ie. implement the get_property method), and make sure the 
widget is in a valid state after construction with g_object_new(), then 
libglade can support your widget with no additional code.

Simply make sure the _get_type() function for your widget has been 
called before calling glade_xml_new().  Then libglade will be able to 
construct widgets of that type if it finds them in the input file.

This doesn't give you a nice UI to build your widget in glade, but you 
can easily hand edit the .glade file afterwards.  The glade-3 project is 
working on a rewrite of glade that also makes use of properties, which 
should make it a lot easier to support custom widgets like this.

James.

-- 
Email: james daa com au
WWW:   http://www.daa.com.au/~james/